Chevrolet TrailBlazer 4.2-Liter V-6

• 1). Remove the radiator shroud with a 3/8-drive ratchet set. Remove the drive belt from the engine using the tensioner assembly to loosen the belt. Use the breaker bar on your ratchet if you need extra leverage. Place a drip pan underneath the front of the engine.
  
  
• 2). Remove the pulley attached to the front of the water pump. Use a screwdriver to lock the pulley in place as it will want to spin as you try to remove the bolts. Remove the fastener bolts for the water pump. Use the screwdriver to lightly pry the water pump from the engine.
  
  
• 3). Inspect the water pump and the water pump mounting surface thoroughly. If the engine shows signs of scarring where the water pump was mounted, replace the pump completely. If the water pump shaft gives any resistance to spinning when off the vehicle, replace the entire water pump.
  
  
• 4). Clean the mounting surface where the water pump seals to the engine. Use a wire brush to remove any excess gasket material from the engine surface and the water pump if you are not replacing it. Spray a rag with engine parts cleaner and wipe the water pump mounting surfaces, both on the engine and the pump.
  
  
• 5). Place a light string of high-temp gasket sealer on the engine mounting surface. Repeat this process on the water pump. Place the new gasket on the water pump and use your fingers to gently align the gasket to the pump. Set the water pump flush with the engine.
  
  
• 6). Install the water pump mounting bolts in a star pattern using just your fingers to start them. Do not tighten any bolts until all of the bolts are in and the water pump is properly aligned. Tighten the mounting bolts using 40 to 60 foot-pounds of torque. Do not over-tighten the bolts as you will ruin the seal and the new gasket.
  
  
• 7). Reinstall the water pump pulley and the vehicle drive belt. Fill the radiator with coolant and start the vehicle. Allow the engine to warm for at least 15 minutes. Top off the radiator with coolant. Top off the radiator overflow bottle with coolant. Dispose of spilled coolant at your local auto parts provider or any oil change shop. These facilities are equipped to properly dispose of coolant. Reinstall the radiator shroud.
  
  

Chevrolet TrailBlazer 5.3 Liter V-8

• 1). Set a drain pan underneath the front of the engine. Remove the radiator shroud, which is the plastic cover over the radiator. Remove the serpentine belt with the tensioner assembly. Squeeze the two coolant hoses on the water pump shut, using flat vise grips or radiator hose pliers. Remove the two coolant hoses mounted on the water pump.
  
  
• 2). Remove the water pump pulley bolts using a 3/8-drive ratchet and socket set. Use a screwdriver to prevent the pulley from spinning freely. Remove the water pump mounting bolts using the same tools. Pry the water pump from the engine using a screwdriver for leverage if necessary.
  
  
• 3). Inspect the water pump shaft. Spin the shaft and visually inspect it for any warping or bending in the shaft and the internal pump parts. Inspect both mounting surfaces on the water pump and the engine. Replace the water pump if you see any signs of defects or flaws in the water pump.
  
  
• 4). Scrape the gasket material and residue from both the water pump and engine mounting surfaces. Use a straight razor blade or small wire brush. Spray engine parts cleaner on a rag and wipe both mounting surfaces for a smooth adhering surface for reinstallation.
  
  
• 5). Add a thin line of gasket sealer to the mounting surface on the water pump. Gently place the new gasket on the water pump and align the mounting bolt holes. Add a thin line of gasket sealer to the engine mounting surface.
  
  
• 6). Place the water pump back on the engine. Start the mounting bolts in place using only your fingers. Do not tighten down or torque any bolts until all of the mounting bolts are in place and started. Tighten the bolts between 45 and 60 foot-pounds of torque. Do not over-tighten the bolts to avoid damaging the new gasket and the seal between the pump and the engine.
  
  
• 7). Reattach the water pump pulley. Tighten the pulley bolts between 45 to 60 foot-pounds of torque. Reinstall the serpentine belt.
  
  
• 8). Reassemble the hoses onto the water pump. Fill the radiator with coolant. Start your vehicle's engine and visually inspect the water pump seal. Allow the TrailBlazer to run for at least 15 minutes before shutting it off. Top off the radiator and the radiator overflow bottle. Reinstall the radiator cap and the radiator shroud when the coolant system is sufficiently full.